The statements in this section merely provide background information related to the present disclosure. Accordingly, such statements are not intended to constitute an admission of prior art.
Known vehicle systems use hybrid powertrain architectures to generate tractive torque using plural torque-generative devices including internal combustion engines and one or more non-hydrocarbon-fueled torque machines, which may include electric machines that transform electric power to mechanical torque. Hybrid powertrain architectures may be configured to transfer tractive torque to an output member through a transmission device. Known hybrid powertrain architectures include series-hybrid configurations, parallel-hybrid configurations, and compound-split hybrid configurations. Electric machines operative as motors and generators are controlled to generate torque inputs to the transmission independently of a torque input from the internal combustion engine. The electric machines may react and transform vehicle kinetic energy transmitted through the vehicle driveline to electrical energy that is storable in an electrical energy storage device employing regenerative braking and other methods. A control system monitors various inputs from the vehicle and the operator and provides operational control of the powertrain, including controlling transmission operating range state and gear shifting, controlling operation of the engine and the torque machines, and regulating the electrical power interchange among the electrical energy storage device and the electric machines to manage torque and rotational speed outputs of the transmission.
Components employed in hybrid powertrain systems have operating limits that are determined based upon a physical capacity to perform an intended function, including, e.g., transferring torque, transferring electric power, or storing electric energy. Service life of a component may be reduced if a respective operating limit is violated. Operating limits include electric motor speed limits, engine speed limits, pinion gear speed limits of planetary gear sets, and battery power limits. Operating limits further include motor torque limits, engine torque limits, clutch torque limits, and belt torque limits. Operating limits also include electric limits including voltage and current limits. By way of example, service life of a high-voltage battery may be limited if either over-voltage or under-voltage limits are exceeded. Similarly, a service life of a switch in an electric inverter may be limited if an operating temperature is exceeded. Similarly, service life of a hydraulically activated clutch may be limited if an operating pressure is exceeded.
Control systems for hybrid powertrain systems impose system constraints based upon the operating limits to determine control parameters for operation during ongoing operation.